n = int(input())
c = list(input())

count = 0
r = c.count('R')

for i in range(r):
  if c[i] == 'W':
    count += 1
print(count) n = int(input()) n int(input()) int input() input c = list(input()) c list(input()) list input() input count = 0 count 0 r = c.count('R') r c.count('R') c.count c count 'R' for i in range(r):
  if c[i] == 'W':
    count += 1 i range(r) range r if c[i] == 'W':
    count += 1 c[i] == 'W' c[i] c i 'W' count += 1 count 1 print(count) print count count += 1 1 count count = 0 0 count r = c.count('R') c.count('R') r c = list(input()) list(input()) c n = int(input()) int(input()) n
n = int(input())
c = list(input())

count = 0
r = c.count('R')

for i in range(r):
  if c[i] == 'W':
    count += 1
print(count)